Magnetic head using a magnetoresistance effect based on ferromagnetic junction, and magnetic recording/reproducing apparatus using the same

Abstract

A first magnetic layer ( 3 ) is laminated on a magnetic yoke film ( 2 ) forming a closed magnetic circuit containing a magnetic gap so as to be magnetically coupled to the magnetic yoke film ( 2 ), and a magnetic separation layer ( 4 ), a second magnetic layer ( 5 ) and an antiferromagnetic layer ( 6 ) are laminated on the first magnetic layer ( 3 ). Further, a pair of electrodes ( 1, 7 ) are formed so that the laminate comprising the above layers is sandwiched between the electrodes. A permanent magnet film 8 is disposed to apply a bias magnetic field to the first magnetic layer ( 3 ). The magnetic separation layer ( 4 ) is formed of an insulator. Tunnel current is made to flow between the electrodes ( 1, 7 ) through the magnetic separation layer ( 4 ), and magnetic signals in the magnetic yoke film ( 2 ) are detected by using the antiferromagnetic tunnel magnetoresistance effect that the tunnel current is varied in accordance with variation of the difference in the magnetization direction between the first magnetic layer ( 3 ) and the second magnetic layer ( 5 ).

What is claim is:  
     
       1. A magnetic head comprising: 
       a magnetic yoke film forming a closed magnetic circuit containing a magnetic gap;  
       a first magnetic layer which is laminated on said magnetic yoke film and magnetically coupled to said magnetic yoke film;  
       a second magnetic layer laminated on said first magnetic layer through a magnetic separation layer; and  
       a pair of electrodes which are formed so that a laminate comprising said magnetic yoke film, said first magnetic layer, said magnetic separation layer and said second magnetic layer is sandwiched therebetween, wherein a bias magnetic field is applied to said first magnetic layer by a permanent magnet film disposed adjacent to said first magnetic layer in respect of the direction parallel to a surface of said first magnetic layer, and a magnetic signal in said magnetic yoke film is detected by using a magnetoresistance effect based on the difference between the magnetization direction of said first magnetic layer and the magnetization direction of said second magnetic layer.  
     
     
       2. The magnetic head as claimed in  claim 1 , wherein the magnetization direction of said second magnetic layer is fixed. 
     
     
       3. The magnetic head as claimed in  claim 2 , wherein the magnetization direction of said second magnetic layer is fixed by laminating an antiferromagnetic layer on said second magnetic layer. 
     
     
       4. The magnetic head as claimed in  claim 1 , wherein said magnetic separation layer is formed of insulator, tunnel current is made flow between said pair of electrodes through said magnetic separation layer, and there is used a ferromagnetic tunnel magnetoresistance effect that the tunnel current is varied in accordance with variation of the difference between the magnetization direction of said first magnetic layer and the magnetization direction of said second magnetic layer. 
     
     
       5. The magnetic head as claimed in  claim 1 , wherein a coil is wound around said magnetic yoke film. 
     
     
       6. A magnetic recording/reproducing apparatus for recording/reproducing information through a magnetic head on/from a magnetic recording medium, wherein said magnetic head is the magnetic head as claimed in  claim 1 , and said magnetic head is movable in a direction parallel to the surface of said magnetic yoke film relative to said magnetic recording medium. 
     
     
       7. The magnetic recording/reproducing apparatus as claimed in  claim 6 , wherein the information is recorded/reproduced while the gap between the magnetic recording medium and the magnetic head is kept to be 40 nm or less. 
     
     
       8. The magnetic recording/reproducing apparatus as claimed in  claim 6 , wherein the magnetic recording medium is a flexible tape-shaped medium obtained by forming a magnetic recording layer on a flexible substrate. 
     
     
       9. The magnetic recording/reproducing apparatus as claimed in  claim 8 , wherein the magnetic recording layer is a magnetic thin film formed by a physical vapor deposition method. 
     
     
       10. The magnetic recording/reproducing apparatus as claimed in  claim 6 , wherein the magnetic recording medium is a flexible disc-shaped medium obtained by forming a magnetic recording layer on a flexible substrate. 
     
     
       11. The magnetic recording/reproducing apparatus as claimed in  claim 10 , wherein the magnetic recording layer is a magnetic thin film formed by a physical vapor deposition method. 
     
     
       12. The magnetic recording/reproducing apparatus as claimed in  claim 6 , wherein the magnetic recording medium is a medium obtained by forming a magnetic recording layer on a substrate of a rigid body. 
     
     
       13. The magnetic recording/reproducing apparatus as claimed in  claim 12 , wherein the magnetic recording layer is a magnetic thin film formed by a physical vapor deposition method. 
     
     
       14. A magnetic head comprising: 
       a magnetic yoke film forming a closed magnetic circuit containing a magnetic gap, said magnetic yoke film also serving as a first magnetic layer;  
       a second magnetic layer laminated on said first magnetic layer through a magnetic separation layer; and  
       a pair of electrodes formed so that a laminate comprising said first magnetic layer, said magnetic separation layer and said second magnetic layer is sandwiched by said electrodes, wherein a bias magnetic field is applied to said first magnetic layer by a permanent magnet film disposed adjacent to said first magnetic layer in respect of the direction parallel to a surface of said first magnetic layer, and a magnetic signal in said magnetic yoke film is detected by using a magnetoresistance effect based on the difference between the magnetization direction of said first magnetic layer and the magnetization direction of said second magnetic layer.  
     
     
       15. The magnetic head as claimed in  claim 14 , wherein the magnetization direction of said second magnetic layer is fixed. 
     
     
       16. The magnetic head as claimed in  claim 15 , wherein the magnetization direction of said second magnetic layer is fixed by laminating an antiferromagnetic layer on said second magnetic layer. 
     
     
       17. The magnetic head as claimed in  claim 14 , wherein said magnetic separation layer is formed of insulator, tunnel current is made flow between said pair of electrodes through said magnetic separation layer, and there is used a ferromagnetic tunnel magnetoresistance effect that the tunnel current is varied in accordance with variation of the difference between the magnetization direction of said first magnetic layer and the magnetization direction of said second magnetic layer. 
     
     
       18. The magnetic head as claimed in  claim 14 , wherein a coil is wound around said magnetic yoke film. 
     
     
       19. A magnetic recording/reproducing apparatus for recording/reproducing information through a magnetic head on/from a magnetic recording medium, wherein said magnetic head is the magnetic head as claimed in  claim 14 , and said magnetic head is movable in a direction parallel to the surface of said magnetic yoke film relative to said magnetic recording medium. 
     
     
       20. The magnetic recording/reproducing apparatus as claimed in  claim 19 , wherein the information is recorded/reproduced while the gap between the magnetic recording medium and the magnetic head is kept to be 40 nm or less. 
     
     
       21. The magnetic recording/reproducing apparatus as claimed in  claim 19 , wherein the magnetic recording medium is a flexible tape-shaped medium obtained by forming a magnetic recording layer on a flexible substrate. 
     
     
       22. The magnetic recording/reproducing apparatus as claimed in  claim 21 , wherein the magnetic recording layer is a magnetic thin film formed by a physical vapor deposition method. 
     
     
       23. The magnetic recording/reproducing apparatus as claimed in  claim 19 , wherein the magnetic recording medium is a flexible disc-shaped medium obtained by forming a magnetic recording layer on a flexible substrate. 
     
     
       24. The magnetic recording/reproducing apparatus as claimed in  claim 23 , wherein the magnetic recording layer is a magnetic thin film formed by a physical vapor deposition method. 
     
     
       25. The magnetic recording/reproducing apparatus as claimed in  claim 19 , wherein the magnetic recording medium is a medium obtained by forming a magnetic recording layer on a substrate of a rigid body. 
     
     
       26. The magnetic recording/reproducing apparatus as claimed in  claim 25 , wherein the magnetic recording layer is a magnetic thin film formed by a physical vapor deposition method.